The present invention relates to a low noise package storing type engine working machine, wherein the escape of engine noise, including intake noise and air passing through a radiator, is reduced. The low noise package includes an engine and a working machine.
As shown in FIG. 2, an engine working machine 1xe2x80x2 contains a working machine (e.g., a compressor, a dynamo or so on). The working machine 4 is connectedly attached to a water-cooling type engine 3. The working machine 4 and water-cooling engine 3 are contained in a package 2, and known in the art. Air, after exchanging heat at a radiator 5, is led into the package 2, used for externally cooling the engine 3 and the working machine 4, and then exhausted through ventilating vents (exhausting vents) 2a. The vents 2a are formed at the side and bottom surfaces of the package 2.
In these circumstances, because noise is generated when air for radiator 5 is led into the package 2, sound absorption material is placed at an air leading port 11 of the radiator 5. However, because the air Axe2x80x2 is led from the air leading port 11 to radiator 5 almost directly, noise generated in the air leading port 11 escapes unencumbered, and consequently, the noise reducing effect is small.
Further, external cooling wind Bxe2x80x2 of the engine working machine 1xe2x80x2 is generated by a cooling fan 6, which intakes heat exchange air Axe2x80x2 after leaving radiator 5. However, the cooling fan 6, which feeds cooling wind, is disposed upstream of the engine 3 and the working machine 4, and therefore there is no special member to guide wind towards the engine 3 and the working machine 4. To ensure proper cooling of engine 3 and working machine 4, a lot of exhausting vents 2a are formed at the side and bottom surfaces of the package 2. This generates a smooth flow of external cooling wind Bxe2x80x2 for the engine 3 and the working machine 4. However, this creates a problem that noise generated from the engine 3 and so on escapes to the outside through the many exhausting vents 2a with cooling wind Bxe2x80x2, which has circulated in the package 2. Moreover, a problem arises because the air Axe2x80x2 used for the heat exchanging of the radiator 5 has been warmed at the time of passing through the radiator 5. Thus, the air Axe2x80x2, if being used as the external cooling wind Bxe2x80x2 for the engine 3 and the working machine 4, has little cooling effect.
Additionally, there is the problem of engine intake noise associated with an engine working machine. Conventionally, to reduce air intake noise, a resonator 8xe2x80x2 is attached to a midpoint of an intake pipe of an engine.
However, the noise reduction effect of this resonator 8xe2x80x2 is limited to a specific frequency band. Conventionally, space limitations provide for only one resonator in the narrow space of the package, which can lead to insufficient reduction of the noise in the case when there are more than one peak frequency bands of intake noise. Attaching more than one resonator to the intake pipe causes enlargement of the engine working machine. Also, it seems that more than one resonator would reduce noise of multi-frequency bands and improve the total noise reducing effect; however, in fact, each resonator vibrates by resonation, which creates noise and consequently adds to the overall radiant noise. Far from reducing the noise, such an arrangement of more than one resonator results in increased radiant noise sources and consequently acts so as to diminish the noise reduction effect.
An object of the invention is to provide a low noise package storing type engine working machine.
Therefore, according to the present invention, first, a low noise engine working machine formed by storing a radiator and a cooling fan for leading heat exchange air for the radiator in a package together with an engine and a working machine is constructed such that a storing space for the engine and the working machine excluding a ventilating port communicating to a space between the radiator and the cooling fan is shielded from an air leading space to which air is led after being passed through the radiator by the cooling fan, and a cooling air leading port for externally cooling the engine and the working machine is formed in a part of the package so that outside air led from the cooling air leading port passes the storing space for the engine and the working machine and is exhausted from the ventilating port to the air leading space to which air led after having passed through the radiator.
Next, as for an air leading port for leading air to the radiator, according to the present invention, a plurality of forward-and-backward rows of soundproof walls are formed parallel in a direction of flow of air therein, and air passages are formed in each row of the soundproof wall so as to be placed alternately with air passages formed in the forward or backward adjacent row of soundproof wall in the direction perpendicular to the flow of air. In this regard, a sectional shape of the soundproof wall formed between any adjacent two of said air passages in each row of the soundproof wall may be formed in a substantial V-like shape which opens toward the side of the radiator.
Further, as for the reduction of engine intake noise, according to the present invention, the engine intake noise reduction apparatus comprising a plurality of unified resonators is attached to an intake pipe of an engine in an engine working machine formed by storing a radiator and a cooling fan for leading heat exchange air for the radiator in a package together with the engine and a working machine. In this connection, a resonation pipe of each resonator in said noise reduction appliance may be formed as a multiplexed pipe.
Said and other features and advantages of the invention will be apparent more fully from the following description and the accompanying drawing.